In recent years, memory systems comprising a nonvolatile memory have become widespread. One of the memory systems has been known as a solid state drive (SSD) based on NAND flash technology.
In the server of a data center, an SSD is used as a storage device.
High I/O performance has been required for the storage device used in a host computing system such as a server.
For some reason, recently, a new interface between a host and a storage device has been proposed.
In some cases, recent storage devices have been required to write different types of data to different write destination blocks.
However, when the number of write destination blocks available at the same time is increased, the number of write buffers necessary for temporarily storing the write data to be written to individual write destination blocks should be also increased. Normally, the capacity of a random access memory in a storage device is limited. Thus, in some cases, it is difficult to prepare a sufficient number of write buffers in a storage device. Therefore, in the actual base, the number of write destination blocks available at the same time is limited.